IL-1 plays an important role in atherosclerosis, and alters expression of a number of genes involved in atherosclerotic plaque development and progression. Smooth muscle cells play important roles in atherosclerotic plaque formation and stability, so this study was undertaken to determine the global effects of IL-1b on gene expression in smooth muscle cells in vitro. Overall design: Cultured rat aortic smooth muscle cells were treated with IL-1b (2.5 ng/mL) or vehicle (0.1% BSA) for 24 hours prior to harvest.